Automatic choke for firearms



April 27, 1954 H. E. GOTTERSON AUTOMATIC CHOKE FOR FIREARMS Filed Sept. 24, 1948 FIG. 2.

FIG. 8

FIG. 6.

FIG. IO.

M M m mr mm 5 m W M Patented Apr. 27, 1954 UNITED STATES PATENT OFFICE AUTOMATIC CHOKE FOR FIREARMS Herbert E. Gotterson, Brooklyn, N. Y.

Application September 24, 1948, Serial N 0. 50,991

4 Claims. 1

This invention relates to means for varying the choke of guns, such as shot guns, which function by virtue of the emission-of high pressure gases from the muzzle upon discharge of the gun.

One object of the invention is to provide a choking mechanism whose action is independent of the recoil or kick of the gun.

Another object is to provide a choking device which eliminates the need for passage of discharge gases through small openings and to thereby avoid the possibility of any such openings becoming clogged or plugged.

Another object is to provide a variable choke gun which will be sturdy and will not become warped at the muzzle.

Another object of the invention is to provide such a device which may be used inconjunction with a recoil stabilizer.

The attainment of these objects is accomplished by the features set forth in the description below and in some of the claims but the various modifications as shown are but illustrations of the spirit and scope of the invention and may be altered in many ways without departure from the scope of the invention as set forth in the claims.

The inventive features are set forth in connection with a choking device which briefly described includes a collet member forming a continuation of the muzzle of a gun barrel to which the device is secured and a sleeve member therearound, the two members being mounted for longitudinal movement of the barrel which will substantially cause an opening and closing of the collet. One of said members is provided with an opening or bore equal to or slightly larger than the bore of the barrel proper so that wedding or other matter passing through said opening will partially close same for an instant and the pressure of discharge gases will move that member forward with respect to the other member and alter the choke.

In the accompanying drawing showing, by way of example, several of many possible embodiments of the invention,

Fig. 1 is a longtiudinal sectional view of one form of the invention showing the device in open choke position.

Fig. 2 is an end view of the collet as .shown in Fig. 1.

Fig. 3 shows the cooperation of a wad with sleeve as shown in Fig. 1;

Fig. 4 shows the device of Fig. 1 in choked position;

Fig. 5 is an end view of the collet in choked position;

Fig. 6 shows a modification of the device of Fig. 1 wherein a recoil compensator is provided;

Figs. 7 and 8 are longitudinal sectional views of another form of invention in closed and open choke positions respectively;

Fig. 9 is a transverse sectional view of the forms of Figs. 7 and 8 the-section being taken substantially along the line 9-9 of Fig. 8 looking in the direction of the arrows of said line, and

Fig. 10 shows yet another form of the invention.

In the invention as shown in Fig. '1 a collet H! is secured fast on the muzzle end portion of a gun barrel H by any suitable means such as brazing or thread at [2. The forward portion of the collet is provided with a plurality of longitudinal slits I-l dividing the collet to form tangs 15 so that the effective internal diameter of the collet, or the muzzle of the gun since the interior of the collet smoothly joins the interior wall of the barrel l I, may be varied by radial movement of the tangs. Normally the tangs are sprung to flare slightly outwardly at their forward ends as in Figs. 1 and 2. It is important however that slits should not be wide enough to permit any shot from the gun to enter therein. The flaring of the tangs is conveniently enabled by the provision of an external circumferential weakeninggroove l-6 near the end of the barrel I 1. By such provision the tangs or collet may be of such thickness and strength that the outer or forward end portions thereof are not distorted or warped by normal use of the gun and yet the collet may be opened and closed without the use of a prohibitive amount of force. An external bead 18 at the outer end portions of the collet or tangs strengthens the tangs where they are normally subjected to the greatest wear.

The muzzle end of the barrel H and the normally flaring collet it are surrounded by a sleeve l9 longitudinally slidable thereon. The inner forward walls of the sleeve are tapered or sloped complementary to the flare of the collet as at 25) so that forward motion of the sleeve constricts the collet and rearward motion releases the collet and permits the tangs to open outwardly by spring action.

overhanging the outer end of the collet is an inner annular flange 2! on the sleeve to provide a hole 22 of approximately the same diameter, though slightly greater, than the maximum internal diameter of the collet. In retracted position of the sleeve, the flange 2 I is near and may nearly even touch the end of the collet.

When the gun is fired with the collet and sleeve in open choke position, matter from the load of the gun, such as wedding 24 as shown in Fig. 3,

partially, for an instant, closes the hole 22 in the end of the sleeve so that discharge gases impinge against the rear wall 25 of the flange so as to move the sleeve forward on the barrel and collet. Such motion constricts the collet to choked posi tion as shown in Figs. 4. and 5. The sleeve i9 is retained on the barrel by an inwardly turned lip 26 which strikes against the rear portion 28 of the collet. For reattaining open choke position the sleeve is manually returned to the posi tion of Fig. 1.

In another form of the invention as shown in Fig. 6 the collet I is the same as described above and the sleeve I9 is substantially as described of sleeve l9 except that the flange 2| assumes the form of a tubular extension 29 having an internal diameter approximately equal to that of hole 22. This form provides an annular ledge 30 against which gases may impinge as against th flange wall 25. Gas ports 31 are provided in the extension 29 to divert a portion of the discharge gases and so reduce recoil of the gun. Due to the fact that time for passage of the wedding through the extension 29 is greater that that required for passage past the relatively thin or short flange 2i, the duration of gas impingement on the ledge 39 will be greater than on the wall 25, and hence a portion of the gases may be defiected or bled before they reach the ledge 36. This is accomplished by means of ports or vents 32 through the sleeve just rear of the ledge.

My choking mechanism depends entirely on the direct expansion of gases in a substantially instantaneously closed cylinder, the cylinder being the barrel and sleeve with the latter closed off at the outer end by the presence of shot and wadding passing through the hole 22 or extension 29.

In yet another form of the invention as shown in Figs. 7 and 8 the sleeve 34 is secured fast to the barrel l l, and the collet 35 is slidable therein. The interior of the forward end of the sleeve is flared as at 36 so that upon forward motion of the collet 35 the choke is enlarged as in Fig. 8. The sleeve 34 is provided with longitudinal slots 38 through which studs 39 secured to the collet pass. These studs limit the forward motion of the collet and also serve as exposed handles for retracting the collet when desired. It will be noted that the mechanism of Figs. 7 and 8 remains in open choke position after a shot is fired at closed choke position until manual retraction to the latter.

The device of Fig. is similar to that of Figs. '7, 8 and 9, the only difference being that the bore of the sleeve is tapered inwardly as at 45) to have an opposite camming action from the flared sleeve 34. Thus forward motion of the collet has the effect of constricting the muzzle.

In all forms of my invention the basic prin ciple of operation is the same. In each form the barrel and a slidable part associated therewith cooperate to form an extendable cylinder. In Figs. 1 through 6 a sleeve is the slidable part; in Figs. '7 through 10 it is the collet. In all forms the extendable or slidable part is normally open but becomes partially plugged for an instant by the wadding of the load. During this instant when the sliding part is plugged, the expanding gases may be said to elongate the cylinder or push the slidable part forward and so by cam action alter the choke of the gun.

The above action might be considered also to be due to the drag of gases and other matter such as shot and wadding rushing past the slid- 4 ing part and dragging the latter along. Such may be a more accurate accounting for the operation since none of the gases must pass through any small orifice or slot.

I have found that my device is not dependent on recoil action of the gun and hence variations of powder or shot charge, and the manner in which the gun is held do not affect its operation. This fact permits the use of a. recoil compensator such as shown in Fig. 6 as the extension 29. Also in the forms of Figs. 1 through 6 no massive sleeves are required for inertia effects and the collet tangs may be made very heavy to withstand stress and erosion for there is always a sufficient force to move the sleeve.

Furthermore I have found in testing a. device as shown in Fig. 1, in which the movement of the sleeve from open to closed position was inch, the device operated in an excellent manner. However when the flange 2! was removed the sleeve movement was only inch, and the choking effect was nil.

It will be noted that the tangs of the collet are in substantial contact with each other from one end to the other at their lateral faces when the collet is closed. The collet is made initially substantially as shown in Figs. 4 and 5 with a tapered bore and a bead l8 as nearly perfectly circular at the inner and outer periphery as is possible. Slits I4 are then cut 0.012 inch wide, and the tangs sprung to flare as in Figs. 1 and 2. These characteristics prevent lead dust and the like from being wedged in the slits when gun is fired with closed choke, in contradistinction to the clogging of the slits when the latter are much wider. Furthermore the present structure insures a larger area of contact between the sleeve and the collet bead as the tangs are constricted. If, for example, the outer peripheries of bead sections of Fig. 2 had common centers of curvature, ridgy burrs would be formed when the collet is constricted and tend to sieze on the sleeve.

The invention claimed is:

1. In combination, a gun barrel; a collet secured fast on the muzzle end of the barrel and having a tapered forward portion; a sleeve around the collet longitudinally slidable thereon and having a cammed inner wall in engagement with the forward Portion of the collet whereby forward motion of the sleeve constricts the collet, said sleeve having an internal flange on the forward end portion thereof and overhanging the forward end of the collet to form an opening of approximately the same diameter as the internal diameter of the collet in open position. 1

2. A combination as in claim 1 and means for limiting forward movement of the sleeve to prevent jamming of the collet and sleeve.

3. A choking device for guns comprising a collet member adapted to be secured on the end of a un barrel as an extension of the barrel and having tangs normally flared outwardly, a sleeve longitudinally slidably mounted on the collet member for closing the tang thereof. said sleeve being provided with an inwardly directed flange forward of the ends of the tangs to provide an opening through which wadding of a charge load in a gun may pass and which will be. partially closed by the wadding as the latter passes through the opening.

4. An automatic choking device for a gun barrel comprising a collet member having a bore and atangs. and a sleeve around the collet member and longitudinally slidable thereon to constrict same, the sleeve having an inwardly turned flange forward of the tangs and out of contact with the tangs and provided with an opening about the size of said bore through which a load may pass whereby gases emerging from the tang end of the member will tend to drag the flange and sleeve forward.

Name Date White Dec. 31, 1937 Number Number 10 Number Name Date Sidberry Oct. 25, 1938 Kitzmiller Jan. 20, 1942 Finlay et a1 Apr. 9, 1946 Whedon Mar. 18, 1947 Egleson Nov. 16, 1948 Schmeling June 26, 1951 FOREIGN PATENTS Country Date Germany Sept. 2, 1896 France Feb. 21, 1908 

